A turbine and compressor section within a turbomachine, such as a gas turbine, may include a rotor assembly comprising a rotating disk (rotating around a rotation axis provided by a rotor shaft) and a plurality of rotor blades circumferentially disposed around the disk and connected to the disk. Each rotor blade may comprise a root section, an airfoil section and a platform positioned in a transition area between the root section and the airfoil section. The root section of a blade may be received in complementary shaped recesses within the disk for mechanically mounting the rotor blade. The platform of the blade may laterally extend outwards and collectively may form a flow path of a working fluid passing through the rotor stage. The working fluid may flow primarily along the axial direction which may be defined as the direction of the rotation axis.
The rotor blade may be situated in a compressor stage of a turbine stage of the gas turbine.
The rotor blade comprises the airfoil section which impacts or is in contact with the working fluid to compress the working fluid upon rotation of the rotor blade (when the rotor blade is in the compressor section) or is driven by working fluid to cause rotation of the rotor blade (when the rotor blade is in the turbine section). During compression of the working fluid or impacting of the high temperature working fluid discharged from a combustor the rotor blade, in particular the airfoil section of the rotor blade, may receive heat energy causing the rotor blade, in particular the airfoil section of the rotor blade, to heat up. In order to carry away heat energy, the airfoil section of the rotor blade may be internally cooled using a cooling fluid, such as a gas, for example steam or compressed cooling air. For this purpose, the cooling fluid must be supplied to an inside of the airfoil section of the rotor blade.
U.S. Pat. No. 6,092,991 discloses a gas turbine blade having a platform and a turbine wheel plate in which cooling passages are arranged in a plurality of rows and connected to one another in a blade trunk section of a moving blade and a supply side passage and a discharge-side passage are formed in a blade root section.
U.S. Pat. No. 2,641,439 discloses a blank, from which a turbine blade is to be formed, wherein the blank includes a root portion having an opening for introducing cooling air into grooves of the blade. Three ridges run as far as the outer end of the opening, where they terminate and their upper surfaces merge with the surface of the blank.
U.S. 2006/0153679 A1 discloses cooling channels for directing cooling fluid through the turbine blade to remove excess heat to prevent premature failure.
It has been observed that cooling of a rotor blade, in particular an airfoil section of a rotor blade, requires a large amount of cooling fluid or may be ineffective either resulting in a decreased efficiency of the gas turbine or leading to damages to the rotor blades due to excess heating of the rotor blades during operation of the gas turbine.
There may be a need for a root section of a rotor blade, for a rotor blade, for a rotor blade arrangement and for a method for supplying a cooling fluid to a rotor blade, in particular to be used in a turbine stage of a gas turbine, wherein the efficiency of the cooling is increased and wherein damages to the rotor blade may be avoided.